Phosphoric acid metal cleaning and rust preventing solution



William K.

signor NITED STATES PATENT OFFICE PHOSPHORIC ACID METAL'CLEANING AND RUST PREVENTING SOLUTION to The Schweitzer, East Cleveland, Ohio, as-

Grasselli Chemical Company,

Cleveland, Ohio, a corporation of Delaware No Drawin The present invention relates to 5 Claims.

improvements in cleaning metallic surfaces and protecting them from rusting, particularly those of articles of ferrous metals and consists in novel cleaning solu- 5 tions containing phosphoric acid as the rust removing and preventive agent and oil sulfonation products, which facilitate the action of the phosphoric acid on the metal surfaces.

As is well known, aqueous phosphoric acid has the properties of dissolving rust, scale and other mineral incrustations found on the surfaces of metallic articles when they have p assed through the ordinary fabricating operations prior to painting or otherwise finishing them; co-incidentally with such dissolving of rust, etc., the phosphoric -acid attacks, to a slight extent, the metal itself to form a beneficial film of metal phosphate which protects the metal from further rust or otherwise being attacked by moist atmosphere Such a protecting phosphate film however, does not form wherever the metal surface has come in contact with grease, oil or shows handmarks, such spots being liable to rust'after the ph osphoric acid treatment and at the same time paints and other coatings do not adhere well to such incompletely protected spots. I have found on the oily or greasy spots of the that oil sulfonation products act metal surface cleaning them, whereby they become amenable to the action of phosphoric acid, which then forms a continuous protecting film over the whole surface. Such sulfonated oils on the other hand,

donot interfere with the removal scale, etc., and do not prevent the attack of the of rust, oxide,

metal by the phosphoric acid to produce the phosphate film.

The organic products which I have found useful for this purpose are-the sulfonatiori products of animal and vegetable oils which are the glycerids of high molecular fatty acids. Physically,

- these products are characterized by being water soluble and generally liquid at ordinary temperatures.

While readily soluble in water, such sulfonation products-are less soluble in a phosphoric acid solution ofthe concentrations usually employed for cleaning and rust preventing I,- therefore,

usesucli emulsions which are eas th metallic surfaces and remove with water. I

It is, however, more convenient mixture a water purposes.

1 can emulsify these sulfonation products with the phosphoric acid solution and ily applied to d by washing to add to the soluble common solvent for g. Application July 1, 1932, Serial No. 620,552

aqueous phosphoric acid and the sulfonated oil in amounts sufilcient to produce a homogeneous solution. Methyl alcohol, ethyl alcohol, acetone, etc., are convenient solvents for the production of a homogeneous solution of phosphoric acid 5 and a. sulfonated oil in water.

The exact amounts of sulfonated oil which can be incorporated in this manner in aqueous phosphoric acid and will produce an efficient cleaning and rust preventive solution, is not particl0 ularly critical and amounts of from 1 to 5% of the solution have given excellent results.

I have, for instance prepared a base solution of 1 volume phosphoric acid, 1 volume denatured alcohol or other similar solvent, 1.5 vol- 15 ume water, to which I added from 1 to 5% of one of the following sulfonation products: sulfonated castor oil, sulfonated corn oil, sulfonated cotton seed oil, sulfonated fish oil, sulfonated olive oil, sodium salt of sulfonatedcorn oil, sodium salt of 20 sulfonated cotton seed oil, ammonium salt of sulfonated, cotton seed oil, etc.

Pieces 'of sheet iron slightly rusted and coated with oil were immersed in such solutions; they were readily wet, the rust thereon dissolved quick- 25 ly and left a rust preventing film of phosphate on and completely covering the metal.

It will be understood that when using the salts of the sulfonated oils, such as mentioned above, the free sulfonic acids will be formed in the phos- 30 phoric acid solutions and for this reason the salts X will be the full equivalents of the sulfonic acids themselves. 7

I claim: v

1. A metal cleaning and rust preventing solu- 35 tion comprising aqueous phosphoric acid, a sulfonated vegetable'oil and ethyl alcohol.

2. A metal cleaning and rust preventing solution comprising 1 volume of 85% phosphoric acid, a 1 volumeof denatured alcohol, 1 volumes of 40 water and from 1 to 5% of the total of a sulfonated vegetable oil. I

3. A metal cleaning and rust preventing solution comprising aqueous phosphoric acid, a suljonated animal oil and ethyl alcohol.

4. A metal cleaning and rust preventing solution comprising aqueous phosphoric acid and a sulfonated glycerid of a high molecular fatty acid.

5. A metal cleaning and rust preventing solution comprising aqueous phosphoric acid, a sul- 50 fonated glycerid of a high molecular fatty acid and a water soluble, .common solvent for phos- \phoric acid and said sulfonated acid. 

